196 OF MANURE. 



besides containing the most nitrogen, contains also 

 the most phosphates ; and if rotation of the crops 

 were adopted, they would be most abundant. By 

 using, at the same time, bones and the lixiviated 

 ashes of wood, the excrements of animals might be 

 completely dispensed with. 



When human excrements are treated in a proper 

 manner, so as to remove the moisture which they 

 contain without permitting the escape of ammonia, 

 they may be put into such a form as will allow them 

 to be transported even to great distances. 



This is already attempted in many towns, and the 

 preparation of night-soil for transportation consti- 

 tutes not an unimportant branch of industry. But 

 the manner in which this is done is the most in- 

 judicious which could be conceived. In Paris, for 

 example, the excrements are preserved in the houses 

 in open casks, from which they are collected and 

 - placed in deep pits at Montfaucon, but are not sold 

 until they have attained a certain degree of dryness 

 by evaporation in the air. But whilst lying in the 

 receptacles appropriated for them in the houses, the 

 greatest part of their urea is converted into car- 

 bonate of ammonia; lactate and phosphate of am- 

 monia are also formed, and the vegetable matters 

 contained in them putrefy ; all their sulphates are 

 decomposed, whilst their sulphur forms sulphuretted 

 hydrogen and hydro-sulphate of ammonia. The mass, 

 when dried by exposure to the air, has lost more 

 than half of the nitrogen which the excrements 

 originally contained ; for the ammonia escapes into 

 the atmosphere along with the water which evapo- 

 rates ; and the residue now consists principally of 

 phosphate of lime, with phosphate and lactate of 

 ammonia, and small quantities of urate of magnesia 

 and fatty matter. Nevertheless, it is still a very 

 powerful manure, but its value as such would be 

 twice or four times as great, if the excrements before 

 being dried were neutralized with a cheap mineral 

 acid. 



